17 Example of software change Application framework Drawlets –adds graphical display to a host...

17 Example of software change

• Application framework Drawlets – adds graphical display to a host application

• Drawing canvas – lines, free-hand lines, rectangles, rounded

rectangles, triangles, pentagons, polygons, ellipses, text boxes, images

© 2012 Václav Rajlich Software Engineering: The Current Practice Ch. 17 1

Drawlets - features

• More than 100 classes, 35 interfaces and 40,000 lines of code– originally implemented by Kent Beck, Ward

Cunningham– later ported into Java– “perfect API”

– http://www.rolemodelsoft.com/aboutUs/ drawlets.htm


http://www.rolemodelsoft.com/aboutUs/drawlets.htm

http://www.rolemodelsoft.com/aboutUs/drawlets.htm

The host application

• Responsible for providing an instance of the drawing canvas, toolbars, and tool buttons

• Class SimpleApplet is a host application – is a part of the Drawlet library – SimpleApplet runs in any browser


SimpleApplet window


Top classes


SequenceOfFigures

ShapeTool

EllipseToolRectangleTool RectangularCreationTool PG_RectImageTool

Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar

LocatorConnectionHandle

PrototypeConstructionTool

SelectionTool ConstructionTool

StylePalette

LabelTool

Figure

Change Request

• Implement an owner for each figure. – An owner is the user who put the figure onto the

canvas, and only the owner should be allowed to modify it.

– At the beginning of a session, the users input their ID and password and they are the owners of all figures that were created during the session.

• This change will make SimpleApplet more versatile and useful– support for cooperative work


Concepts

• Implement an owner for each figure. – An owner is the user who put the figure onto

the canvas, and only the owner should be allowed to modify it.

– At the beginning of a session, the users input their ID and password and they are the owners of all figures that were created during the session


Concept classification


irrelevant external significant implement x owner x figure x user x canvas x allowed x modify x beginning x session input x ID x password x created x

Locating figure properties


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Wrong way


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Backtrack


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Right way


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Wrong way


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Backtrack


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Summary


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Actualization


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Change propagation


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Propagation - 1


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Propagation - 2


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Propagation - 3


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Propagation - 4


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Propagation - 5


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Propagation - 6


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Propagation - done


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Unit Tests

• 385 unit tests• 1369 assertions • 4800 lines.


Functional tests

• Draw– figure drawn on the canvas, for all figures

• Select – figure is selected

• Move – figure is moved to a different location

• . . .– 141 functional test cases


Creation of functional tests

• Record/playback tool for Java applications • Tool Abbot used to run the functional tests


Phase of actualization

• New unit tests for new classes • New functional tests for the new

functionality• During the change propagation, the old

tests that were impacted by the change were updated.


Test suite maintenance

• Tests from the old version that are not affected by the change are kept as regression tests for the future

• Obsolete tests are removed• Tests of the new features are added after

the change


Results

• Base line– production code 17800 lines – unit test code 4800 lines.

• Change– 91 lines of production code (0.5%) were

modified– 124 lines (2.5%) of the test code– approximately 1.4 test code lines per modified

production code line.


Refactoring

• Long change propagation is a problem• it would be advantageous to shorten it

• Refactoring can shorten the change propagation • move code affected by change into fewer

classes• split the roles


Propagation


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

OwnerIdentity

SimpleListener

LabelTool

Figure

Moving the code

• Each class that creates new figures has the function basicNewFigure(...) – two main parts:

• create a new figure • if the figure was created at wrong location, move it

• We refactored a new method called moveFigure(...)– made it a member of the base class ConstructionTool


Refactoring impact


SequenceOfFigures

ShapeTool


Locator

CanvasTool

AbstractFigure

SimpleDrawingCanvas

DrawingCanvas

ToolPalette

SimpleApplet

ToolBar




StylePalette

LabelTool

Figure

Splitting of roles

• Same method used in two different roles– the same code can do both jobs

• Propagating change highlights the differences– only one of the roles needs to be updated – the other one can stay unchanged– splitting the two roles and updating only one

of them shortens the propagation


Splitting the roles

• Function move(...) in AbstractFigure is used in two ways– to move the figure as requested by the user

• must check user identity– as a part of the new figure creation

• does not need to check user identity

• We split move(...)and secureMove(…)


Numerical data


No refactoring Move function Splitting

Classes added 2 2 2

Interfaces modified

1 1 1

Classes modified

13 8 5

LOC modified

91 95 87

Conclusions

• Splitting up a method into two similar methods may require least work

• Minus: A new set of unit tests must be created, thus test code is duplicated.

• Minus: More effort is required to create new tests compared to the effort required to adapt existing tests to their changed implementation.

• Possible problem: Does Role splitting strategy lead to system degeneration?


17 Example of software change Application framework Drawlets –adds graphical display to a host...

Documents

Transcript of 17 Example of software change Application framework Drawlets –adds graphical display to a host...